Regulation of KOR in the NAc alters C48/80-induced scratching behaviors. A, Experimental configuration shows guide cannula implantation in the NAc core. B, Schematic diagram of the timeline for the experiment. C, Bilateral intra-NAc core infusion of KOR agonist U50488 (0.26 μg/0.3 μl per side) significantly attenuates C48/80-induced scratching behaviors (n = 9 mice for each group, t₍₁₆₎ = 3.749, **p = 0.0018). D, NAc administration of U50488 does not affect the time spent in open arms in mice with treated with C48/80 (U = 30.50, p = 0.3980). E, Same as D for the open arms entry (U = 35.50, p = 0.6853). F, U50488 does not affect the time spent in central zone in mice with treated with C48/80 (U = 31.50, p = 0.4489). G, Same as F for the travel distance (U = 28, p = 0.2973). H, Intra-NAc core preinfusion of KOR antagonist nor-NBI (0.25 μg/0.3 μl per side) increases the low-dose (10 μg/50 μl) of C48/80-induced scratching behaviors (n = 12–13 mice for each group, t₍₂₃₎ = 2.429, *p = 0.0234). I, nor-NBI did not affect the time spent in open arms in mice treated with C48/80 (10 μg; t₍₂₃₎ = 0.03014, p = 0.9762). J, Same as I for the open arms entry (U = 57, p = 0.2611). K, nor-NBI did not affect the time spent in central zone in mice treated with C48/80 (U = 65, p = 0.4936). L, Same as K for the travel distance (U = 51, p = 0.1519).